It is well known that carotenoids are natural pigments that occur abundantly in the plant and animal kingdoms and which, in some cases, have also been produced by synthetic means. Other carotenoids can be synthetically produced and do not appear to occur in nature. Many important carotenoids are employed as pigments in the food and feedstuff industries, e.g., for coloring egg yolk, poultry, fish, and crustacea, notably in the cases of ethyl beta-apo-8′-carotenoate (CAROPHYLL® Yellow), astaxanthin (CAROPHYLL® Pink), and canthaxanthin (CAROPHYLL® Red). For this purpose the carotenoid pigments are added to the animals' rations as a method of imparting an enhanced and aesthetically more acceptable visual impression of color, be it in the animal integuments, such as the skin, shanks, and beaks of poultry and the skin, scales, and shells of fish and crustacea, as appropriate, subcutaneous fat of poultry and the meat of fish and crustacea, or in such animal products as eggs (egg yolk). The enhancement of pigmentation depends on the particular light-absorbing conjugated double bond system of the carotenoid concerned, the degree of ease with which the carotenoid is taken up into the animal body following consumption of the carotenoid-enriched feed (“deposition rate”), and the concentration of the carotenoid or any metabolites in the target animal body tissue or product, among other factors. However, one cannot predict from the structure of the selected carotenoid how effectively it functions as a pigment in this area of application. A further factor is the stability of the carotenoid, e.g., towards atmospheric oxidation, light, temperature, and dampness, in an animal feedstuff under normal storage conditions.
In poultry an acceptable level and quality of pigmentation is desired for the integuments of the birds destined for consumption, e.g., broilers, and for the egg yolks of laying poultry, e.g., laying hens. Materials are used to enhance yolk color, for example, because consumers prefer deeply (particularly rich golden yellow) pigmented yolks. The visual appearance of food is an important factor in the assessment of quality. In many parts of the world broilers and ornamental birds, for example, are more aesthetically acceptable if their integuments, particularly skin, shanks, and beaks, and, in the case of broilers, also subcutaneous fat satisfy certain criteria of pigmentation. The need for supplementary pigmentation is especially prevalent today in view of the reduction of grass consumption in the modern methods of intensive poultry rearing. The use of low fiber, high energy feeds makes the production of well-pigmented poultry and egg yolks difficult.
The pigmentation of fish meat and integuments, especially in various species of trout and salmon, and the meat and integuments of crustacea, e.g., crabs, lobsters, and shrimps, is achieved by feeding the fish and crustacea carotenoid-enriched feed preparations, thereby making the edible products more attractive to consumers.
Moreover, alimentary products such as dairy products, e.g., butter and cheese, and such cosmetic products as lipsticks are pigmentable by incorporation of carotenoids at a suitable stage of the pertinent production processes.